You wish to revoke write access for all groups and named users on a file. Which command will make the correct ACL changes?

The `-x` option is used to remove an ACL entry, not to modify or revoke specific permissions within existing entries.

The `-x` option would remove the entire mask entry, rather than modifying its permissions to revoke write access.

The `setfacl -m mask::rx afile` command correctly uses the `-m` option to modify an ACL entry and specifically targets the `mask::` entry, setting its permissions to `rx` (read and execute). By limiting the mask to `rx`, it revokes write access for all named user, named group, and owning group entries whose effective permissions are governed by the mask.

This command attempts to modify permissions for all named users and groups directly, which is not the standard or efficient way to revoke a specific permission across all relevant ACL entries; the mask is designed for this purpose.